JP2003245974A - Method for manufacturing metallic pipe lined with olefin resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metallic pipe lined with an olefin resin by which an olefin resin is applied to the inner face of a metallic pipe for lining with an extremely wide operating range, using a general-purpose olefin resin, without defining a special blend and limiting an operating range, in lieu of an olefin resin whose shape memory is poor. <P>SOLUTION: This method for manufacturing a metallic pipe lined with an olefin resin comprises the first step to mold a double-layered plain pipe for lining with an adhesive resin applied to the outer face of an olefin resin pipe, the second step to insert the double-layered plain pipe for lining into the metallic pipe after folding the plain pipe, the third step to bring the plain pipe into contact tightly with the inner face of the metallic pipe by applying a pressure to the inner face of the plain pipe after inserting the double-layered plain pipe into the metallic pipe and the fourth step to heat the outer face of the metallic pipe at higher than a melting point of the adhesive resin and at lower than a melting point of the olefin resin pipe under such a state that the plain pipe is brought into contact tightly with the inner face of the metallic pipe and thereafter, bond the inner face of the metallic pipe and the outer face of the plain pipe together by cooling the entire plain pipe down to lower than its melting point. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an olefin-based resin-lined metal pipe used for water supply, hot water supply, drainage, fire extinguishing, air conditioning, etc., in which an olefin-based resin is lined on the inner surface of the metal pipe. .

[0002]

2. Description of the Related Art Pipes used for water supply and drainage include steel pipes or vinyl chloride resin for improving corrosion resistance, etc. on the inner surface of steel pipes which have been subjected to surface treatment such as chromate treatment, zinc plating treatment and primer treatment. A resin-lined pipe lined with polyethylene resin or the like is used.

Of these, in the production of olefin resin lining pipes, a powder coating method has been used in which a heated steel pipe is powder-coated with resin powder to form a lining layer on the inner surface of the steel pipe. . However, this powder coating method requires expensive equipment for coating. In addition, since it is difficult to evenly fuse the resin powder to the inner surface of the steel pipe, pinholes are likely to occur, and when used as water pipes for a long period of time, corrosion resistance will deteriorate, and product performance problems will occur. There was also.

Further, since olefin resins do not have shape memory characteristics unlike vinyl chloride resins, various proposals for imparting shape memory characteristics have been made. For example, Japanese Patent Laid-Open No. 2001
JP-A-131354 discloses that a lining resin is a blended resin of an olefin resin and crystalline polystyrene, which is reduced in diameter or folded between the melting temperatures of both resins and deformed, and then cooled and solidified to fix the shape. A method of imparting sex has been proposed. In addition, Japanese Patent Laid-Open No. 2001-62
In Japanese Patent No. 915, a crystalline thermoplastic resin having a glass transition temperature of 25 ° C. or lower is deformed at a temperature of 100 ° C. lower than a melting completion temperature or higher and a Vicat softening temperature or lower, and then cooled and solidified to fix the shape. Therefore, a method of providing shape memory has been proposed.

[0005]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In the method described in Japanese Patent Application Laid-Open No. 001-131354, a step of blending two resins with a kneader and an extruder is required, and there are restrictions on cost and manufacturing space. In addition, Japanese Patent Laid-Open No.
Both the methods described in Japanese Patent Application Laid-Open No. 2001-131354 and Japanese Patent Application Laid-Open No. 2001-62915 have a problem that it is very difficult to perform lining because the temperature range for deformation processing is limited.

Therefore, the present invention solves the above-mentioned problems of the prior art, and is a general-purpose olefin resin without special blending or limitation of the operating range with respect to the olefin resin which is generally a resin having poor shape memory. An object of the present invention is to provide a method for producing an olefin-based resin-lined metal pipe, in which the olefin resin can be lined on the inner surface of the metal pipe in an extremely wide operating range.

[0007]

The invention according to claim 1 is
A first step of molding a two-layer raw pipe for lining in which an outer surface of an olefin resin pipe is coated with an adhesive resin, a second step of folding the two-layer raw pipe for lining and then inserting the pipe into a metal pipe, After inserting the two-layer raw pipe for lining into the metal pipe, a third step of applying pressure to the inner face of the raw pipe to bring the raw pipe into close contact with the inner face of the metal pipe, and with the raw pipe being brought into close contact with the inner face of the metal pipe , Heating from the outer surface of the metal pipe at a temperature not lower than the melting point of the adhesive resin and not higher than the melting point of the olefin resin pipe, and then cooling until the melting point of all the two-layer raw pipe for lining is not more than the inner face of the metal pipe. The fourth to bond the outer surface of the tube
It is a method for producing an olefin-based resin-lined metal tube comprising steps.

According to a second aspect of the present invention, a two-layer raw pipe for lining having a shape memory property, which is stretch-molded in the axial direction of the pipe and is obtained by coating an outer surface of an olefin resin pipe with an adhesive resin, is formed. In the first step, the two-layer raw tube for lining,
The second step of inserting into the metal pipe, after inserting the raw pipe into the metal pipe, by heating from the outer surface of the metal pipe above the melting point of the adhesive resin layer and below the melting point of the olefin resin pipe, the olefin resin A third step of expanding the diameter of the pipe to bring it into close contact with the inner surface of the metal, and a fourth step of adhering the inner surface of the metal tube and the outer surface of the original tube by cooling to below the melting points of all the raw tubes.
It is a method for producing an olefin-based resin-lined metal tube comprising steps.

According to a third aspect of the invention, the resin used for the olefin resin pipe is polyethylene.
The density of the polyethylene is 0.92 to 0.95 g / c
m is ³ is a manufacturing process according to claim 1 or 2 olefinic resin lining metal pipe according. Olefin resin lined pipes are often used for water and hot water applications. Especially for hot water applications, heat shock between room temperature and a maximum of 95 ° C or thermal expansion and contraction causes large stress at the interface between the metal layer and the resin lining layer. Interfacial peeling may occur due to this repeated stress over a long period of time. This is because this stretching stress can be minimized by setting the polyethylene density within the above density range. In the present invention, the density means JIS.
Measured by the test method specified in K7112.

The invention according to claim 4 is the method for producing an olefin resin-lined metal pipe according to claim 3, wherein the melting point difference between the polyethylene and the adhesive resin is 3 to 25 ° C. This is because when polyethylene is used, it is easy to completely melt only the adhesive resin layer if the melting point difference is within the above range.

Examples of the above polyethylene include Ziegler-Nat
Examples thereof include those obtained using ta or Metlocene as a catalyst, and the production method may be any of a high pressure method, a gas phase method, a solution method, and a slurry method. It may be a copolymer with another olefin component (preferably having 4 to 8 carbon atoms).

Further, in the invention according to claim 5, the resin used for the olefin resin pipe is a polypropylene resin, and the melting point difference between the polypropylene resin and the adhesive resin is 15 to 35 ° C. The method for producing an olefin resin-lined metal pipe according to 1 or 2. If a resin tube having an above melting point difference of more than 35 ° C. and an adhesive resin are used, the softening temperature of the adhesive resin becomes too low, resulting in poor heat resistance. If the melting point difference is smaller than 15 ° C., the lining resin pipe is softened when the lining is heated to a temperature above the melting point of the adhesive resin to increase the heat shrinkage force, and the metal pipe and the lining are made of the adhesive resin. This is because the adhesive strength of the resin pipe cannot be obtained sufficiently.

Examples of the polypropylene resin include a homopolymer of propylene, or propylene,
Ethylene, butene-1, pentene-1, hexene-1,
A block copolymer with an α-olefin such as 4-methyl-pentene-1 may be mentioned.

According to a sixth aspect of the invention, the density of the adhesive resin is 0.89 to 0.94 g / cm ³ , and the MF is MF.
R is 1-10 g / 10min, It is a manufacturing method of the olefin resin lining metal pipe of Claims 1-5.
This is because the MFR of the adhesive resin exhibits a so-called physical anchoring effect in which the resin layer enters into the fine irregularities of the metal due to the fluidity after melting, and improves the adhesion with the metal tube.

Particularly, when the resin used for the olefin resin pipe is polyethylene, 0.91 to 0.94 is used.
g / cm ³ is preferable, and in the case of polypropylene resin, 0.89 to 0.91 g / cm ³ is preferable.

Incidentally, the MFR means JIS K7210.
190 ° C, test load 2.16
It is measured under the condition of kgf.

Further, the invention according to claim 7 is characterized in that the means for heating from the outer surface of the metal pipe is an electromagnetic induction heating method, and the method for producing an olefin resin-lined metal pipe according to any one of claims 1 to 6. Is.

The thickness of the olefin resin tube layer is not particularly limited and is preferably 0.5 to 3.0 mm, although it varies depending on the required performance depending on the application.

The thickness of the adhesive resin layer is not particularly limited, and it is preferably 0.2 to 1.0 mm, although it varies depending on the required performance depending on the application.

Examples of the adhesive resin include maleic anhydride-modified olefin resin, ethylene-maleic anhydride copolymer resin, ethylene-maleic anhydride-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid. Examples thereof include a copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, and a maleic anhydride-modified olefin resin is preferable in view of total cost performance. If necessary, additives such as antioxidants, flame retardants, pigments, fillers, antistatic agents, lubricants, tackifiers, and other resins should be added to these olefin resins and adhesive resins. Can be done.

If necessary, the olefin resin tube and the adhesive resin may be filled with a layered silicate. The above-mentioned layered silicate means a silicate mineral having exchangeable cations between layers, and usually fine flaky crystals having a thickness of about 1 nm and an average aspect ratio of about 20 to 200 are aggregated by ionic bonds. It will be done.

The type of the layered silicate is not particularly limited,
Examples include smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite; natural minerals such as vermiculite, halloysite, sepiolite; synthetic mica such as swelling mica (swelling mica). To be These layered silicates may be natural or synthetic. Preferably, montmorillonite and synthetic mica are used.

The exchangeable cations existing between the layers of the layered silicate may be ion-exchanged in advance with a cationic surfactant or the like. In particular, when a non-polar resin of a polyolefin resin is used, it is better to make the layers hydrophobic by, for example, cation exchange using a cationic surfactant, between the layered silicate and the polyolefin resin. It is preferable because a high affinity can be obtained.

As described above, a material in which the layers of the layered silicate are ion-exchanged with a cationic surfactant having a hydrophobic group is referred to as "organized layered silicate". Is preferably used because it is more easily dispersed in the resin than the non-organized layered silicate. There is no particular limitation on the substance that makes the above-mentioned layers hydrophobic in advance, and a commonly used cationic surfactant is used, and examples thereof include a quaternary ammonium salt and a quaternary phosphonium salt. Preferably, a quaternary ammonium salt having an alkyl chain having 8 or more carbon atoms is used. When the alkyl chain having 8 or more carbon atoms is not contained, the alkylammonium ion has strong hydrophilicity, and it may be difficult to sufficiently depolarize the layers of the layered silicate.

The above quaternary ammonium salt is, for example,
Examples thereof include lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, trioctyl ammonium salt, distearyl dimethyl ammonium salt, di-hardened tallow dimethyl ammonium salt, and distearyl dibenzyl ammonium salt.

The cation exchange capacity of the layered silicate is not particularly limited, but is preferably 50 to 200 meq / 100 g. If it is less than 50 meq / 100 g, the amount of the cationic surfactant intercalated between the crystal layers by ion exchange may be small, and the layers may not be sufficiently depolarized. If the amount is more than the equivalent amount / 100 g, the bond strength between the layers of the layered silicate becomes strong, and it may be difficult to delaminate the crystal flakes. The cation exchange capacity is the amount of cations that can be exchanged with 100 g of the layered silicate.

The layered silicate is preferably added in an amount of 1 to 15 parts by weight, more preferably 2 to 13 parts by weight, based on 100 parts by weight of the resin component. If it is less than 1 part by weight, the effect of reducing the linear expansion coefficient of the resin is small, and 1
If it exceeds 5 parts by weight, the formability, tensile strength, ductility, etc. of the adhesive resin layer will decrease and the cost will increase.

In the present invention, the outer surface of the olefin resin pipe is coated with an adhesive resin to obtain a two-layer raw pipe for lining. If the overall thickness of the two-layer raw pipe for lining is too thin, the inside of the metal pipe is When heating the surface in the lining process. The shape cannot be maintained, and if it is too thick, folding or the like becomes difficult, so 0.5 to 3 mm is preferable.

If the tensile elastic modulus of the above-mentioned two-layer raw pipe for lining is too low, blisters are likely to occur during hot water passage, and if it is too high, folding becomes difficult.
~ 1.5 GPa is preferred.

The method for coating the above-mentioned adhesive resin on the outer surface of the olefin resin tube layer is not particularly limited, and when the two-layer raw pipe for lining is extrusion-molded, it is formed in multiple layers in a mold; olefin resin A method of coating and extruding the outer surface after forming the tube layer; a method of winding an adhesive resin extruded in a sheet shape around the olefin resin tube layer, etc., but simplifying the process and the olefin resin tube layer and the adhesive resin layer From the viewpoint of the reliability of the interface, it is preferable to form multiple layers in the mold.

The metal pipe used for the resin lining pipe of the present invention is not particularly limited, but a steel pipe is usually preferable. In addition, the metal tube surface is plated, pre-treatment such as blast treatment, pickling treatment, chemical conversion treatment,
Those that have been subjected to a surface treatment such as a primer treatment are preferable in terms of adhesion and the like.

According to the first aspect of the invention, the two-layer raw pipe for lining is folded and then inserted into the metal pipe. The two-layer raw pipe is folded only by the inner cross-sectional area of the metal pipe into which the raw pipe is to be inserted. This is because the metal tube has a smaller cross-sectional area and is inserted into the metal tube.

The folded shape of the two-layer original pipe for lining is not particularly limited, such as U-shaped, Ω-shaped, and petal-shaped, but it is a shape that gives as much distortion as possible to the portion that deforms the original pipe. Ω type shape is most desirable.

The original tube is folded at room temperature immediately before it is inserted into the metal tube, and the amount of strain applied to the tube is within the elastic deformation limit of the olefin resin 1 to 20.
% Is preferable.

By doing the above, when the original pipe is folded, the strain can be applied to the portion that deforms the pipe as uniformly as possible. That is, when folding the original pipe,
When plastic deformation occurs, when pressure is applied to the inner surface of the two-layer raw pipe for lining to bring it into close contact with the inner surface of the metal pipe in the process described below, uneven thickness occurs, and a good olefin resin lining pipe is obtained. I can't.

The elastic deformation region limit is the amount of strain reaching the yield point of the Strain-Stress curve when a tensile test is performed.

Then, after the insertion of the folded two-layer raw pipe for the lining into the metal pipe is completed, pressure is applied to the inner face of the raw pipe to bring the raw pipe into close contact with the inner face of the metal pipe. By doing so, the adhesive resin on the outer surface of the original pipe can be brought into close contact with the inner surface of the metal tube with a uniform pressure.

According to the second aspect of the present invention, a two-layer raw pipe for lining, which is obtained by coating an adhesive resin on the outer surface of an olefin resin pipe stretch-formed in the axial direction of a pipe having a shape memory property, is used in a metal pipe. To insert. In this case, it is preferable that the raw pipe has an inner diameter slightly smaller than the inner diameter of the metal pipe.
By doing so, it can be inserted into the metal tube in its original shape without being folded.

Then, in the invention of claim 1, the temperature of the adhesive resin layer is above the melting point and below the melting point of the olefin-based resin pipe in the state where the raw pipe is closely attached to the inner surface of the metal pipe. It is possible to bond the metal pipe and the olefin resin pipe by heating from above, and then cooling so that the melting point of all of the two-layer raw pipe for lining is below the melting point. This is because if the temperature becomes higher than the melting point of the olefin resin tube, the olefin resin tube layer will not be able to retain its shape on the inner surface of the metal tube and will sag, so that an appropriate lining tube cannot be obtained.

Further, in the invention of claim 2, after inserting the raw pipe into the metal pipe, by heating from the outer surface of the metal pipe above the melting point of the adhesive resin layer and below the melting point of the olefin resin pipe, the resin pipe Has a shape memory property and is stretch-molded in the axial direction, so that the resin tube can be expanded and brought into close contact with the inner surface of the metal tube. After that, the metal pipe and the olefin resin pipe can be bonded by cooling so that the melting point of all of the two-layer raw pipe for lining is below the melting point. This is because if the temperature becomes higher than the melting point of the olefin resin tube, the olefin resin tube layer will not be able to retain its shape on the inner surface of the metal tube and will sag, so that an appropriate lining tube cannot be obtained.

At this time, as a method of heating the lining pipe from the outer surface of the metal pipe, heat transfer heating of a hot air stove or the like may be used, but electromagnetic induction heating is more preferable. By using the electromagnetic induction heating method, it is possible to rapidly heat only the adhesive resin layer to melt the entire surface, and to bring at least 0.5 mm of the olefin resin tube layer to be lined to a temperature equal to or lower than the melting point.

(Operation) In the method for producing an olefin resin-lined metal pipe of the present invention, a two-layer raw pipe for lining, which is obtained by coating the outer surface of the olefin resin pipe with an adhesive resin as described above, is used as a metal pipe. Inserted and in close contact with the inner surface of the metal tube, the temperature of the adhesive resin layer is above the melting point and below the melting point of the olefin resin tube, and heated from the outer surface of the metal tube. Because it cools so that
The olefin resin can be lined on the inner surface of the metal pipe in a very wide range of operating conditions without the complexity of the resin blending process, the problem of cost, and the restriction of the molding temperature range.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described.

Polyethylene is used as the olefin resin pipe.
When used (Example 1) Material used Olefin resin: polyethylene (melting point: 124 ° C., density: 0.929 g / cm ³ , MFR: 0.7 g / 10 m
in) Adhesive resin: Maleic anhydride modified polyethylene (melting point:
120 ° C, density 0.920 g / cm ³ , MFR: 3.0
g / 10min)

Example 2 Olefin resin: polyethylene (melting point: 135 ° C., density: 0.950 g / cm ³ , MFR: 0.7 g / 10 m)
in) Adhesive resin: Maleic anhydride modified polyethylene (melting point:
125 ° C, density 0.949 g / cm ³ , MFR: 1.6
g / 10min)

Comparative Example 1 Using the same materials as in Example 1, the raw pipe was inserted into the steel pipe, and heated from the outer surface of the closely adhered steel pipe to the melting point or higher in the entire length of the olefin resin layer. However, the shape of the original pipe could not be maintained, and an olefin resin-lined metal pipe could not be obtained.

The resin used for the olefin resin pipe is
The adhesive resin has a melting point difference of 15 to 15
In the case of 35 ° C. (Example 3) Block polypropylene (melting point: 167 ° C.), adhesive resin (Mitsui Chemicals, trade name “Admer QF551”, melting point: 135 ° C.), melting point difference: 32 ° C.

(Example 4) Homopolypropylene (melting point: 170 ° C), adhesive resin (manufactured by Nippon Polyolefin Co., Ltd., trade name "ADTEX ER"
353LA ", melting point: 150 ° C), melting point difference: 20 ° C

Comparative Example 2 Block polypropylene (melting point: 167 ° C.), adhesive resin (Mitsui Chemicals, trade name “Admer QB510”, melting point: 160 ° C.), melting point difference: 7 ° C.

Comparative Example 3 High-density polyethylene (melting point: 132 ° C.), adhesive resin (Mitsui Chemicals, Inc., trade name “Admer XE070”, melting point: 90 ° C.), melting point difference: 42 ° C.

Preparation of metal tube The inner surface of the steel tube was subjected to chemical conversion treatment with zinc phosphate, and the inner surface thereof was surface-treated with an epoxy-based primer (outer diameter: 60.5 m).
m, wall thickness 3.8 mm)

Manufacture of two-layer raw pipe for lining : Using the following equipment, the above-mentioned raw materials were used to coat the outer surface of the olefin resin pipe with an adhesive resin to obtain the following two-layer raw pipe for lining. .

Extrusion equipment used Extruder for olefin resin pipe: Single screw extruder (external diameter 65 m
m, L / D = 25, 45 Kw motor installed) Adhesive resin extruder: Single screw extruder (outer diameter 32 m, L / D)
= 20,15Kw motor mounted) Mold: Multi-manifold type 2-layer pipe Mold Water tank: Vacuum spray water tank (cooling water temperature: 15 ° C)

Dimensions of two-layer raw pipe for lining Outer diameter: 54.0 mm Length: 4 m Olefin resin pipe layer thickness: 1.5 mm Adhesive resin layer thickness: 0.15 mm

Manufacture of lining metal tube (Examples 1 and 2) As shown in FIG.
The layer original pipe P was fixed by the fixing roller 1 and the bar roller 2 and then sequentially folded by the pressing roller 3 to obtain a two-layer original pipe for lining having the shape shown in FIG.

The folded original pipe was inserted into the steel pipe, and when the insertion of the original pipe into the steel pipe was completed, jigs for applying pressure were attached to both ends, and a pressure of 0.1 MPa was applied at room temperature. The inner surface of the steel pipe.

Next, the steel pipe to which the above-mentioned raw pipe is closely attached is
It was continuously supplied to an electromagnetic induction heating furnace set at 0 ° C. and heated from the outer surface of the steel pipe. At that time, the feed rate of the raw pipe is calculated and set by heat transfer analysis based on the heating furnace length so that the temperature of the adhesive resin layer is above the melting point and below the melting point for the entire length of the olefin resin layer. Then, in a shower-type water tank (water temperature 15 ° C.), the resin layer was rapidly cooled so that all the resin layers had a melting point or lower, to obtain an olefin resin-lined metal pipe.

(Comparative Example 1) In the same manner as in Example 1, from the outer surface of the steel pipe to which the raw pipe was adhered, heating was performed at the melting point temperature of the resin pipe over the entire length of the olefin resin pipe, but the shape of the raw pipe could not be retained. However, the olefin resin lining pipe could not be obtained.

(Examples 3 and 4, Comparative Examples 2 and 3) When producing olefin resin pipes, the resin pipes obtained by the above extruder were
The surface temperature was raised to 90 ° C or higher and the melting point or lower, and axially stretched at a strain amount not exceeding the deformation strain amount from the initial outer dimension to obtain a resin pipe 0.89 to 1.8% smaller than the inner diameter dimension of the metal pipe. .

Next, the resin pipe obtained above was inserted into the steel pipe.

Next, the steel pipe having the olefin resin pipe inserted therein is continuously supplied to an electromagnetic induction heating furnace and heated from the outer surface of the steel pipe so that the diameter of the olefin resin pipe is expanded and brought into close contact with the inner surface of the metal. did. At that time, at the melting point of the adhesive resin layer or more, and in the entire length of the olefin resin layer,
Based on the length of the heating furnace, the feed rate of the raw tube is calculated and set by heat transfer analysis so that the melting point will be below the melting point, and then all resin layers will be below the melting point in the shower type water tank (water temperature 15 ° C). Then, it was rapidly cooled to obtain an olefin resin-lined metal tube.

The lining metal pipes obtained from the raw materials of Examples 1 to 4 and Comparative Examples 2 and 3 were cut into 30 cm, and then the resin protruding from the end of the steel pipe was cut to obtain a test piece, which was subjected to a thermal cycle test. The evaluation results of the hot water resistance test are shown in Tables 1 to 4 below. (Evaluation) Cooling / heating cycle test Each of the obtained test pieces was repeatedly immersed for 5 minutes in a tap water tank adjusted to room temperature and 95 ° C., and 500
For each cycle, the state of interfacial peeling at the end and the state of swelling inside the lining steel pipe were visually observed and evaluated.

Heat resistant water test A pipe end anti-corrosion joint was connected to both ends of the obtained test piece, the outer surface of the pipe was put in a water tank adjusted to 25 ° C, and hot water adjusted to 95 ° C was passed to the inner surface. The bulging state inside the lining steel pipe was evaluated by the following visual observation evaluation every one week. ◯: No swelling Δ: Swelling occurs in an area of 20% or less of the inner surface of the lining pipe ×: Swelling occurs in an area of 20 to 50% of the inner surface of the lining pipe XX: Swelling occurs in the entire inner surface

[0064]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0065]

EFFECTS OF THE INVENTION Since the olefin resin lining metal pipe manufacturing method of the present invention has the above-mentioned constitution, it is generally a special blend with an olefin resin which is a resin having poor shape memory. Without limiting the operating range, a general-purpose olefin resin can be used to line the olefin resin on the inner surface of the metal pipe in an extremely wide operating range.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus used in the method for producing an olefin resin-lined metal tube of the present invention.

FIG. 2 is a cross-sectional view showing an example of a raw lining pipe used in the present invention.

Continued front page    (72) Inventor Junichi Yokoyama             2-2 Kamitobagamichocho, Minami-ku, Kyoto             Gaku Kogyo Co., Ltd. (72) Inventor Hideki Sakakibara             75 Nojiri, Ritto City, Shiga Prefecture Sekisui Chemical Co., Ltd.             In-house (72) Inventor Seiichi Enomoto             75 Nojiri, Ritto City, Shiga Prefecture Sekisui Chemical Co., Ltd.             In-house F-term (reference) 3H024 EA01 EC07 ED04 EE01                 4F211 AA03 AA04 AA11 AD03 AD12                       AD20 AG03 AG08 AH43 SA13                       SC03 SD04 SD11 SH06 SH18                       SN07 SP12 SP30 SP41 SW15

Claims (7)

[Claims] 1. A first step of molding a two-layer raw pipe for lining in which an outer surface of an olefin resin pipe is coated with an adhesive resin, the two-layer raw pipe for lining is folded and then inserted into a metal pipe. Second step, after inserting the two-layer raw pipe for lining into the metal pipe, applying a pressure to the inner surface of the raw pipe to bring the raw pipe into close contact with the inner surface of the metal pipe, and the raw pipe on the inner surface of the metal pipe In a state where they are in close contact with each other, and heating from the outer surface of the metal pipe at a temperature not lower than the melting point of the adhesive resin and not higher than the melting point of the olefin resin pipe, and then 2
A method for producing an olefin-based resin-lined metal pipe, comprising a fourth step of cooling the layered pipe to the melting point or less of all of the layers and adhering the inner face of the metal pipe to the outer face of the raw pipe. 2. A first step of molding a two-layer raw pipe for lining, which has a shape-memory property, and which is formed by coating an adhesive resin on the outer surface of an olefin resin pipe stretched and molded in the axial direction of the pipe, for the lining. The second step of inserting the two-layer raw pipe into the metal pipe, after inserting the raw pipe into the metal pipe, and above the melting point of the adhesive resin layer,
And, the third step of expanding the diameter of the olefin resin pipe so as to be in close contact with the inner surface of the metal by heating from the outer surface of the metal pipe at a temperature equal to or lower than the melting point of the olefin resin pipe, and so that the melting point of all of the original pipes is equal to or lower than the melting point. A process for producing an olefin-based resin-lined metal pipe, which comprises a fourth step of cooling the inner surface of the metal pipe to the outer surface of the original pipe by cooling. 3. The resin used for the olefin resin pipe is polyethylene, and the density of the polyethylene is
It is 0.92-0.95 g / cm < ³ >, The manufacturing method of the olefin resin lining metal pipe of Claim 1 or 2. 4. The method for producing an olefin-based resin-lined metal pipe according to claim 3, wherein a melting point difference between the polyethylene and the adhesive resin is 3 to 25 ° C. 5. The resin used for the olefin resin pipe is a polypropylene resin, and the melting point difference between the polypropylene resin and the adhesive resin is 15 to 35 ° C. A method for producing the olefin-based resin-lined metal tube as described. 6. The density of the adhesive resin is 0.89 to 0.9.
The method for producing an olefin-based resin-lined metal tube according to claim 1, wherein the MFR is 4 g / cm ³ and the MFR is 1 to 10 g / 10 min. 7. The method for producing an olefin resin-lined metal pipe according to claim 1, wherein the means for heating from the outer surface of the metal pipe is an electromagnetic induction heating method.